Nobody expects a thick plot or a heavy amount of character development in a non-stop action movie; and if you do, you should not be watching action movies.
The action was high-impact with well-choreographed fight scenes, and there is a good amount of screen time for each of the stars -- which is hard to do with EIGHT of them in this movie. The cameos were also fun to see. Perhaps these cameo actors can be featured with larger roles in future "Expendable" features?
The only "downfall" to this film is the abundant use of computer-generated blood, explosions, and fire. But shoot, if the studio payed-out for standard fake blood, the budget would have at least gone up twenty-five percent.
This is not a necessarily a good "date" movie; but if your date enjoys EXPLOSIONS, hostage-extraction, knives of all sorts, and the beating of cowardly men that abuse women, well it makes for a good time out-on-the-town.